1. Field of the Invention
This invention relates to a method and assembly for inserting a plurality of catheters in vivo in a biological vessel, such as a blood vessel, urethra, or the like. In particular, the method and assembly of the present invention contemplates a single, steerable guidewire inserted into a vessel, and one or more sensor-carrying catheters engaging the guidewire which are independently inserted into the vessel in a building block fashion.
2. Description of the Relevant Art
In the past few years, there has been a sharp increase in the number of diagnostic and therapeutic procedures performed in vivo in fluid carrying biological vessels. For example, since the work of Grunzig in the late 1970's, coronary angioplasty has become a common therapeutic procedure for dilating a region of stenosis (i.e. constriction) in the coronary arteries. Coronary angioplasty is, in many cases, preferable treatment over such alternatives as open heart bypass surgery. In recent years, valvuloplasty has become an acceptable procedure for treating aortic stenosis across a heart valve.
Of course, there are a wide variety of therapeutic procedures for treating various aspects of heart disease in vivo which avoid open heart surgery. Further, diagnostic techniques, such as angiography, have become increasingly sophisticated and reliable in predicting the location and nature of heart disease. A typical angiolocation plasty procedure usually involves a number of discrete diagnostic and therapeutic steps.
Particular problems associated with invasive diagnostic and therapeutic cardiac catheterization techniques include size restrictions of such invasive devices, and also the ability to measure a variety of fluid characteristics. For example, pulmonary artery pressures are conventionally monitored using a flow directed catheter (e.g. Swan-Ganz catheter, see U.S. Pat. No. 3,995,623, incorporated herein by reference) which carries a pressure sensing lumen through the right ventricle into the pulmonary artery. Such right heart analysis is somewhat simplified in that Swan-Ganz catheters typically have an external diameter of about 7 French (2.3 mm), and are easily flow directed to the region of interest in the right heart.
Left heart coronary catheterization is somewhat more difficult in that any diagnostic (i.e. sensor) or therapeutic device cannot be flow directed, but must be advanced against the direction of blood flow either by direct manipulation of the catheter or by advancing it over a steerable guidewire. Conventional therapeutic and diagnostic catheter-mounted devices include a tubular catheter body having an internal lumen throughout its entire length for receiving the guidewire. U.S. Pat. Nos. 4,195,637 and 4,545,390 (incorporated herein by reference) discuss catheters and guidewires. Advancement of conventional, catheter-mounted therapeutic or diagnostic devices along a guidewire around the aortic arch to the branch points of the left and right coronary ostium is not unduly complex, and such conventional catheter-mounted devices can be sized on the order of 6 French. However, for such devices to be subselectively positionable past the coronary ostium requires an external diameter on the order of 3 French (1 mm) and an easily manipulable guidewire. The coronary arterial tree past the ostium is a prime region of interest both for diagnostic and therapeutic (e.g. angioplasty) procedures.
Difficulties with such conventional guidewire-catheters having receiving lumens include: steerability of the guidewire, visualization of the coronary arteries and stenosis, and exchangeability of catheters. Exchangeability of such catheters is a particular problem (e.g. exchanging a conventional angioplasty catheter for an infusion catheter or larger angioplasty catheter) in that the distal tip of the guidewire must be maintained in the selected coronary artery while the exchange takes place. This exchange is typically accomplished using an exchange guidewire having a length (approximately 3 meters) over twice the length of the catheter so that a portion of the exchange guidewire can be held secured while the catheter is slipped over the end of the guidewire.
A major difficulty with such conventional catheters is the practical inability to carry multiple sensors, or a combination of sensors and therapeutic devices. For example, it would be preferable to avoid the necessity of exchange of conventional catheters, which might be accomplished if the catheter carried the desired variety of sensors and therapeutic devices. Such a catheter might include an angioplasty dilating balloon, an infusion lumen, a pressure sensor, a pH sensor, a temperature sensor, a fluid velocity-determining sensor, or any combination thereof. Such a complex catheter which would incorporate a wide variety of sensors and therapeutic devices would be expensive and perhaps oversized. For wide spread use, it is preferable that any invasive catheter be disposable to avoid the painstaking task of cleaning the guidewire receiving lumen or any infusing lumen which is exposed to the blood or other biological fluid. Thus, such a complex multiple device catheter would preferably either be disposable or easily cleaned, and would be sized on the order of 3-4 French external diameter.
Though the heart is a primary anatomical area of interest, other anatomical regions are particularly appropriate for use of such conventional guidewire-receiving catheters for therapeutic and diagnostic use. For example, such conventional catheters are often used in the digestive tract for treating and investigating stomach disorders. Such probe-carrying catheters might be intubated in the alimentary canal over a guidewire into the small intestine. Such probes might include balloon catheters, perfusion catheters, pH and myoelectric probes, or pressure sensors.
Another common invasive use of such guidewire-receiving catheters involves insertion of such catheters into the urinary tract. For example, a catheter carrying several pressure transducers or pressure lumens might be inserted transurethrally into the bladder and slowly withdrawn out of the urethra to determine a urethral pressure profile. As with the coronary catheters discussed above, the size of such catheters is a major restriction and the expense of such multiple sensor catheters is often prohibitive.